The fish are packed with oxygen so i'm sure would be fine for considerably longer than their transit time. I've had mail order fish from SF and collected from them too. Do introduce gently and add your tank water to the bag gradually to avoid any PH shock. Leave the lights off and allow them to setttle in before popping the lights on as they are very timid after travelling.
They do breed but nothing like as much as those horrible pest snails. They are easy to find and pick out too. Maybe sell the on ebay or pass them on to your lfs??
While we are confessing, I love the WCMMS although I share your water probs, however, I wish I didn't have these tropicals lots of guilt and very little reward.